Diabetes Mellitus (DM) and its associated immune dysfunction are well-studied risk factors for adverse surgical outcomes. The literature regarding endoscopic sinus surgery (ESS) is less robust and there have been conflicting reports on post-operative complications and surgical results in this patient population. The purpose of this study was to analyze the impact of diabetes mellitus on outcomes after ESS via rates of post-operative medical intervention in the first 6 months after surgery. This was a retrospective cohort study of 176 subjects who underwent ESS from 2015 to 2019 at a single institution by 2 fellowship-trained rhinologists. Subjects were divided into 2 groups, those with a documented Hemoglobin A1c (HbA1c) >6.5 or diagnosis of DM and those with HbA1C < 6.5. Patient age, demographics, 6-month preoperative HbA1c, surgical status and extent, and 6-monthpostoperative need for steroids and/or antibiotics were collected. Out of n = 176 total patients, n = 39 (22.2%) were categorized into the DM group, which were older (46.4 vs 53.8 years, P = .004) and higher proportion of white patients (89.7% vs 68.6%, P = .008). There were no significant differences between the 2 groups in proportion of revision surgery, surgical extent, and post-operative use of antibiotics or steroids. When including all variables in binary logistic regression for use of postoperative antibiotics or steroids, the only significant variable predicting these outcomes was the extent of surgical resection including sphenoid sinus (P = .001, OR [95% CI] = 4.02 [1.73-9.34]) or frontal sinus (P < .001, OR [95% CI = 9.86 [4.00-24.33]). Patients with DM do not appear to have worse post-operative outcomes outside of the initial 6-month postoperative period.